Thanks Matt, your exactly right. Most club racers don't have a huge budget, and have to build a car for the area they race. The first CRX I had came with a 4.9, and for the tracks I ran it seemed too tight, and I would be shifting at inappropriate points on the track. I went to a 4.7 which was better but still was tight in 2 at L/R and or out of the boot at the Glen. The stock 4.2 was actually very very good at Pocono, but that was about all. When I got hooked up with the 4.5 from Gear-X it seemed to work better than the others.
Also as you indicted a lot has to do with skill, driving style, and car setup, so if you want to go as fast as you can you have to experiment not only with gears, but with wild swings of suspension settings until you find what works for you.